How to measure the optical conductivity of atomically thin crystals is an important but challenging issue due to the weak light-matter interaction at the atomic scale. Photonic spin Hall effect, as a fundamental physical effect in light-matter interaction, is extremely sensitive to the optical conductivity of atomically thin crystals. Here, we report a precision measurement of the optical conductivity of graphene, where the photonic spin Hall effect acts as a measurement pointer. By incorporating with the weak-value amplification technique, the optical conductivity of monolayer graphene taken as a universal constant of $(0.993\pm 0.005){\sigma }_0$ is detected, and a high measuring resolution with $1.5\times {10}^{-8}{\Omega }^{-1}$ is obtained. For few-layer graphene without twist, we find that the conductivities increase linearly with layer number. Our idea could provide an important measurement technique for probing other parameters of atomically thin crystals, such as magneto-optical constant, circular dichroism, and optical nonlinear coefficient.

中文翻译：

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通过光子自旋霍尔效应精确测量原子薄晶体的光导率

由于原子级的弱光物质相互作用，如何测量原子薄晶体的光导率是一个重要但具有挑战性的问题。光子自旋霍尔效应是光物质相互作用的基本物理效应，对原子薄晶体的光导率极为敏感。在这里，我们报告了石墨烯的光导率的精确测量，其中光子自旋霍尔效应充当测量指标。通过结合弱值放大技术，将单层石墨烯的光导率作为$（0.993\pm 0.005）{\sigma }_0$ 被检测到，并具有较高的测量分辨率 $1.5\times {10}^{-8}{\Omega }^{-\mathrm{1个}}$获得。对于没有扭曲的几层石墨烯，我们发现电导率随层数线性增加。我们的想法可以为探测原子薄晶体的其他参数（例如磁光常数，圆二色性和光学非线性系数）提供一种重要的测量技术。